Wind Speed Changes of North Atlantic Tropical Cyclones Preceding Landfall

Landfalling tropical cyclones have been extensively researched, especially their degradation upon coming ashore and the hazardous weather they create along coastlines and farther inland. Many of the factors that weaken storms over land could begin to act when they are still at sea, yet prelandfall intensity change remains poorly documented. This study examined the consistency of prelandfall changes in tropical cyclone intensity throughout the North Atlantic Ocean from 1950 to present. On average, cyclones intensified by 3 m s(-1) less in their final 12 h before landfall than in the 12 h preceding those, on both mainland shores and in the Greater Antilles, while smaller islands showed no such change. Contributions of increasing storm age and poleward movement to this reduction were negligible. Two possible contributing factors to declining intensification before landfall were examined. The presence of a spring-neap tidal pattern of similar to 2 m s(-1) in the prelandfall decline is consistent with tidal mixing influencing ocean temperature on the continental shelf. The tendency for the decline to be greater at night suggested the possible influence of solar heating on tropical cyclones near shore.